16 Sep, 15 tweets, 6 min read
I've seen a lot of chatter about collectively using box fans to - for example - clear smoke from the #wildfires... heck I've even had that thought! So last night I did some fast math:

a 🧵
I live in Seattle suburbs, so we're just going to focus on WA (sorry OR & CA, you're on your own). WA has an area of 71,362 sq miles. Smoke can rise HIGH, but 2km of air should be plenty to breathe, e.g. earthobservatory.nasa.gov/images/144658/…
So we need to move... ~1.3e16 cubic feet of air(!)
A typical box fan is rated for 2500 cfm (cubic ft per min), & draws ~100W of power. Under ideal scenarios, that will move an impressive 3.6 Million cubic feet per day! I want this smoke gone, so 1 day is good. That's a gentle to moderate breeze across WA
So in our simple model, comparing the volume of air over WA to the capacity of 1 fan, we need 3.6 BILLION box fans to clear WA in 1 day. They would draw 5.2e14 W, or (...some very fuzzy math...) about half the power output of the largest nuclear bomb ever detonated.
Huh, that seems fairly untenable. WA generates quite a bit of power, 116 TWh of electricity each year. We'd need like... 70days worth of ALL the power in WA to drive those fans for 1 day.
ok ok, box fans are clearly too small. Seattle *is* "Jet City" afterall...What if we use JET ENGINES?! I was very impressed: the engines in a 777 move a whopping 2 MILLION CUBIC FEET of air PER MINUTE (at takeoff). WOW
So, those are some serious air movers! Swap those big 'ol boys for the 20" box fans, and we'd need... like 4 million jet engines to clear WA in 1 day. Huh.
Jets burn like... 1500 gal of fuel per hour (at cruise), so running those engines for 1 day would burn ~1.6e11 gallons of fuel. That's about 10 years worth of the US annual jet fuel consumption.
statista.com/statistics/197…
And super bad news here. If you burned that amount of jet fuel, you'd produce something like 3.2 trillion lbs of CO2, which is equiv. to 12 days of worldwide CO2 production.

The air would probably *not* be great then...
Well, maybe WA is just too big, & rich Seattle should look out for itself. Let's just clear the Seattle metropolitan area, a meager 5872 sq mi (about 12x smaller than WA). We'd need 298 million fans, or 372 thousand jets.
OK, we get it. The numbers are absurdly large. What is the point? 2 things:
1) to emphasize the scale of energy at play. You can't reroute a hurricane, or move a city's worth of smoke. As w/ climate change, the problem is HUGE, actions by individual ppl aren't the solution
But relatedly, despite the laughable volumes, etc, consider how reasonable these energy scales actually are! 10yrs of jet fuel use, 12 days of CO2 production. 3 months of power for WA, 1/2 the Tsar Bomba...
We DO change the climate w/ the cumulative impact of our lives
2) Our intuition doesn't prepare us for the real scale of the physical world, so people are easily tricked or duped. Your brain can't fathom a trillion of anything (gal of fuel or \$ spent), & this is one way fake news & misinformation spreads.
and collective action *IS* needed to solve these big problems (climate, fascism, healthcare...), but it requires governments & laws & systemic changes. Some Facebook group is prob not a super robust source of information on the scale of problems we're facing.
Don't get mad at your neighbors for not pointing their boxfans north tonight, be mad that the alarm was rung decades ago & we've done little to nothing to address it. Get FURIOUS that our "leaders" deny the problems even exist.
/🧵

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18 Aug
Today a student asked me: How did you get over the worry of asking a "bad" question?

{Mind you, all this is from my extremely privileged life and esp. current position}
I finished college w/ a C average (which I maintain is A OK!), didn't get into any PhD programs, and felt like I never really "got it" in most courses (astro being almost the only exception).
I certainly didn't do enough of the reading, so relied on lectures to give me info... but I really struggled to take "good notes". My notes were garbage, and DISTRACTING. In my masters courses at SDSU I was determined to do better.
20 Mar
Look at this desk
Isn't it neat?
Wouldn't you think my home office’s
complete?
Wouldn't you think I'm a girl
Who doesn’t have COVID19?
Look at this pantry
Treasures untold
Just how much TP can one cabinet hold?
Look at my stockpile you'd think
(Sure) she's got everything
I've got soup cans and ground beef aplenty
I've got cheese-its and fruit snacks galore
(You want chicken kebabs?
I got twenty)
But who cares?
Covid’s here,
I want more